The present invention relates to mechanisms which are used to raise and lower structures, including covers or tops of mobile and immobile dwellings. More particularly, the present invention is directed to cableless extendable and retractable support systems which are used to raise and lower various structures, including covers or tops of mobile and immobile dwellings.
Towable tent campers and pop-up trailers having collapsible roofs are generally known in the art. Prior art mechanisms used for raising and lowering collapsible tops on such structures are generally balky, hard to operate and maintain, and prone to failure. For example, many lifting mechanisms rely on cranks and cables that are exposed to the elements, can accumulate dirt and debris, and can bind, slip and stretch. Mechanisms which are based upon gear driven assemblies are significantly heavier and more expensive to produce.
The following U.S. Patents exemplify known lifting mechanisms: U.S. Pat. No. 5,865,499 to Keyser, U.S. Pat. No. 5,769,485 to Bontrager et al., U.S. Pat. No. 5,704,677 to Steury et al., U.S. Pat. No. 4,981,319 to Gerzeny et al., U.S. Pat. No. 4,362,258 to French, U.S. Pat. No. 4,317,590 to Young, U.S. Pat. No. 4,201,413 to Rowe, U.S. Pat. No. 4,171,843 to Steury, U.S. Pat. No. 3,981,529 to Bontrager, U.S. Pat. No. 3,924,889 to Gogush, and U.S. Pat. No. 3,519,306 to Young.
The present invention provides cable-less extendable and retractable support systems which can be used to raise and lower various structures, including covers or tops of mobile and immobile dwellings.
According to other features, characteristics, embodiments and alternatives of the present invention which will become apparent to those skilled in the art as the description thereof proceeds, the present invention provides a cableless extendable and retractable support system for raising and lower a structure which includes:
a base;
a structure to be raised and lowered relative to the base;
a plurality of telescopic assemblies coupled between the base and structure to be raised and lowered;
a plurality of spring elements having first and second ends with second ends thereof coupled to the plurality of telescopic assemblies; and
a lift tube assembly coupled to first ends of each of the plurality of spring elements, the lift tube assembly including a mechanism which, when activated, selectively extends or retracts each of the plurality of spring elements therefrom and a housing which encloses the entire mechanism that extends and retracts the plurality of spring elements.
According to one embodiment of the invention, the mechanism that extends and retracts the plurality of spring elements includes a drive screw and a driven screw and a pair of opposed push blocks which are mounded on the drive and driven screws, the first ends of each of the plurality of spring elements being coupled to the pair of push blocks.
According to another embodiment of the invention, the mechanism that extends and retracts the plurality of spring elements includes a drum assembly upon which pairs of the spring elements are wound in opposite direction and a drive assembly to rotate the drum assembly.